1. Field of the Invention
This invention relates to a process for removing elemental sulfur from fluids, particularly fuels such as gasoline transported in a pipeline for the transportation of sour hydrocarbon streams. The fluids are contacted with caustic, water, sulfide and optionally elemental sulfur to form an aqueous layer containing polysulfides and a fluid layer having a reduced elemental sulfur level.
2. Description of Related Art
It is well known that elemental sulfur and other sulfur compounds contained in hydrocarbon streams is corrosive and damaging to metal equipment, particularly copper and copper alloys. Sulfur and sulfur compounds may be present in varying concentrations in the refined fuels and additional contamination may take place as a consequence of transporting the refined fuel through pipelines containing sulfur contaminants resulting from the transportation of sour hydrocarbon streams such as petroleum crudes. The sulfur has a particularly corrosive effect on equipment such as brass valves, gauges and in-tank fuel pump copper commutators.
Various techniques have been reported for removing elemental sulfur from petroleum products. For example U.S. Pat. No. 4,149,966 discloses a method for removing elemental sulfur from refined hydrocarbon fuels by adding an organo-mercaptan compound and a copper compound capable of forming a soluble complex with said mercaptan and said sulfur and contacting said fuel with an adsorbent material to remove the resulting copper complex and substantially all the elemental sulfur.
U.S. Pat. No. 4,908,122 discloses a process for sweetening a sour hydrocarbon fraction containing mercaptans by contacting the hydrocarbon fraction in the presence of an oxidizing agent with a catalytic composite, ammonium hydroxide and a quaternary ammonium salt other than hydroxide.
U.S. Pat. No. 3,185,641 describes a method for removing elemental sulfur from a liquid hydrocarbon which comprises contacting with solid sodium hydroxide a hydrocarbon stream having dissolved therein at least 7.6 parts by weight of water per part of sulfur contained therein to yield both a hydrocarbon phase and an aqueous phase. The method is claimed to be effective and convenient for treating gasoline containing from trace to more than 25 ppm sulfur employing temperatures as high as about 140.degree. F. (60.degree. C.).
U.S. Pat. No. 4,011,882 discloses a method for reducing sulfur contamination of refined hydrocarbon fluids transported in a pipeline for the transportation of sweet and sour hydrocarbon fluids by washing the pipeline with a wash solution containing a mixture of light and heavy amines, a corrosion inhibitor, a surfactant and an alkanol containing from 1 to 6 carbon atoms.